The effect of the intervention was modest, with an average infection rate of 21 infections per 10,000 surgeries during the intervention, compared to 36 per 10,000 surgeries prior to the intervention period (difference -15, 95% CI -35 to -2; rate ratio 0.58, 95% CI 0.37-0.92), researcher Loreen Herwaldt, MD, of the University of Iowa Hospitals and Clinic, Iowa City, and colleagues wrote in the June 2 issue of JAMA.

There was no evidence that SSIs caused by other pathogens replaced those caused by SA and there were very few adverse events.

A recent meta-analysis conducted by Herwaldt and colleagues found that a bundle approach to preventing S aureus-related surgical site infections - which included screening for S aureus nasal carriage, decolonizing carriers with intranasal mupirocin and chlorhexidine gluconate bathing, and vancomycin prophylaxis - was associated with lower rates of the infections among methicillin-resistant S aureus (MRSA) carriers.

In an interview with MedPage Today, Herwaldt said screening and decolonization is not widely done before surgery, and when it is done it is usually limited to MRSA.

"Surgical site methicillin-susceptible S aureus infections (MSSAs), like MRSA, are a major cause of post-surgery morbidity," she said.

The study included 20 hospitals operated by the healthcare provider Hospital Corporation of America in nine states and it was designed to determine if the bundle prevention approach is associated with a lower incidence of serious S aureus surgical site infections among patients having cardiac surgeries or hip or knee replacements.

During the pre-intervention period and intervention period, surgical site infection rates were collected for a median of 39 months and 21 months, respectively.

Just 39% of Hospitals Were Fully Compliant

Preoperative screening for MRSA and MSSA typically occurred between 10 and 14 days before surgery, and no longer than 30 days prior to the procedure. Patients who were found to be positive for MRSA or MSSA were asked to apply the topical antibiotic mupirocin intranasally twice a day for up to 5 days and to bathe daily with the germicide chlorhexidine gluconate. MRSA carriers were also treated with vancomycin and cefazolin or cefuroxime for perioperative prophylaxis, while other patients received cefazolin or cefuroxime.

MRSA- and MSSA-negative patients bathed with chlorhexidine-gluconate the night before and morning of their surgeries.

The study was pragmatic, Herwaldt said, meaning that the participating hospitals adopted the bundle protocol to their own resources and practice patterns.

At 3-months, 83% of hospitals were adherent to the bundle, with 39% fully adherent and 44% partially adherent. A statistically-significant decline in complex surgical site infections was seen for hip or knee replacement (17 fewer infections per 10,000 surgeries; 95% CI -39-0; RR 0.48), but the decline was not significant for cardiac surgeries (6 fewer infections per 10,000 surgeries; 95% CI -48 to 8; RR 0.86).

"We did not find evidence suggesting that SSIs caused by other pathogens replaced those caused by S aureus and we identified very few adverse events," the researchers wrote, adding that the study is the largest conducted to date testing an SSI prevention bundle under pragmatic clinical conditions.

Adherence Low In Emergency Surgery Setting

Herwaldt said the decline in SSIs was particularly notable because the baseline rate of complex SSI infections at the hospitals was low (0.36 per 10,000 surgeries).

The findings also suggest that adherence to the full bundle was important, but, not surprisingly, lower for emergency surgeries than for those that were planned.

In an editorial published with the study, JAMA associate editor Preeti N. Malani, MD, of the University of Michigan Health System, Ann Arbor, noted that while the overall reduction in SSIs from the intervention seems modest, "each complex SSI prevented is clinically meaningful."

"For the individual patient, development of a serious SSI after cardiac or orthopedic surgery usually translates into months of parenteral antibiotics, additional surgical procedures, and extended inpatient and subacute care facility stays," she wrote. "The lengthy recovery can negate any benefit provided by the original operation. In a substantial portion, S aureus SSI will contribute to death."

'Additional SSI Prevention Strategies Needed'

Malani cited the fact that the study was conducted at a single health care system with a below-average baseline infection rate as a study limitation.

"It remains unclear what challenges and barriers may present as this bundle is implemented at other institutions," she wrote, adding that this and other important questions remain.

"Although the current findings demonstrate a decrease in S aureus SSIs, the authors did not find a decrease in gram-negative SSIs or complex SSIs caused by any pathogen," she wrote. "This finding might reflect the overall low rate of infection, but also is a poignant reminder that additional strategies are still needed."

Last Updated June 02, 2015

The research was funded by the Agency for Healthcare Research and Quality, the U.S. Department of Health and Human Services and VA Health Services Research and Development.

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